a. Field of the Invention
The present invention generally relates to ablation electrodes and/or catheter assemblies having a mechanism for irrigating targeted areas. The present invention further relates to irrigated catheter assemblies that allow for a parallel irrigation flow path through the incorporation of a flow guide or member on the outer surface of the electrode assembly.
b. Background Art
Electrophysiology catheters have been used for an ever-growing number of procedures. For example, catheters have been used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, a catheter is manipulated through a patient's vasculature to an intended site, for example, a site within the patient's heart, and carries one or more electrodes, which may be used for ablation, diagnosis, or other treatments.
There are a number of methods used for ablation of desired areas including, for example, radiofrequency (RF) ablation. RF ablation is accomplished by transmission of radiofrequency energy to a desired target area through an electrode assembly to ablate tissue at a target site. Because RF ablation may generate significant heat, which if not controlled can result in undesired or excessive tissue damage, such as steam pop, tissue charring, and the like, it is commonly desirable to include a mechanism to irrigate the target area and the device with biocompatible fluids, such as a saline solution. The use of irrigated ablation catheters can also prevent the formation of soft thrombus and/or blood coagulation.
Typically, there are two general classes of irrigated electrode catheters, i.e., open irrigation catheters and closed irrigation catheters. Closed ablation catheters usually circulate a cooling fluid within the inner cavity of the electrode. Open ablation catheters typically deliver the cooling fluid through open outlets or openings on or about an outer surface of the electrode. Open ablation catheters often use the inner cavity of the electrode, or distal member, as a manifold to distribute saline solution, or other irrigation fluids known to those skilled in the art, to one or more passageways that lead to openings/outlets provided on the surface of the electrode. The saline thus flows directly through the outlets of the passageways onto or about the distal electrode member. This direct flow of fluid through the electrode tip lowers the temperature of the tip during operation, rendering accurate monitoring and control of the ablative process more difficult. Accordingly, it is desirable to have a method that allows for cooling of the electrode while providing accurate monitoring and control of the ablative process.
Even for electrode assemblies that are designed with the incorporation of irrigation passageways, if an electrode has a longer length (i.e., for example, over 3 mm), there may be an increased likelihood of developing thrombus caused by protein aggregation and blood coagulation at the tip of the electrode since the standard angled irrigation flow is directed away from the electrode tip and does not reach the longer tip portion or the more distal regions of the electrode due to it length. Moreover, as the length of the electrode increases, the angled fluid passageways provided by an electrode assembly, may be less effective if too much fluid is directed away from the electrode instead of along the body of the electrode to effectively cool the electrode and provide adequate irrigation to prevent the development of thrombus at the distal area of the electrode. Further, for some applications, open flush irrigated ablation catheters with parallel flow may improve the safety of RF catheter ablation by preventing or mitigating protein aggregation and blood coagulation on the surface of the electrode.